Dockett, 33, did not play last season after tearing his ACL. Prior to last season, Dockett earned three Pro Bowl appearances over 10 seasons with Arizona, which drafted him in the third round of the 2004 draft.
In 2013, Dockett recorded 4.5 sacks and 36 tackles.
"We have been very clear about our feelings for Darnell and our desire to have him back," general manager Steve Keim said. "After speaking with him and his representatives, we decided that this move today makes the most sense for both the team and the player and allows each to keep all of its options open."
The decision to part ways with Dockett, who was entering the final season of a four-year, $35.3 million contract, will create $6.8 million in cap room for Arizona. There is a possibility the team could opt to re-sign him.
With Dockett sidelined last season, the Cardinals ranked 13th in the NFL in rushing defense and 24th in total defense. Arizona went 11-5 and finished second in the NFC West.